In the fourth episode of 'Between Two Nines' with Harry and Cheese, the pair see which players need the new Tradie x Storm undies and how well the squad know their teammates.
You get straight into your seat in a car so you get into it but you have to hop onto the bus and then walk to your seat so it would be hopping on as it isn't instant.
You're somewhat correct. Its based on level of ownership. You "get" in the car because its something you own and can use freely but "hop" on the bus as you do not own it and only use it as necessary.